Thus, the deletion, point mutation or reduced expression of MCM8 or MCM9 in cancers that we report here should be tested in patients as a biomarker for predicting a cancer's sensitivity to ICL-inducing agents such as cisplatin or mitomycin C. As a promoter of HR, MCM8 or MCM9 may serve as a bona fide tumour suppressor similar to other genes important for HR, BRCA1 and BRCA2. A cancer-derived point mutation and a naturally occurring SNP on MCM8 associated with POF diminish the functional activity of MCM8 (Fig. 7). The gene discussed is MCM9; the disease is cancer.